Date of Award

8-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Electrical Engineering

Advisor

Makram, Elham

Committee Member

Singh , Rajendra

Committee Member

Groff , Richard

Abstract

In recent years there has been a lot of emphasis on renewable power integration due to environmental issues and to lower the dependence on fossil fuels. The presence of renewable sources in the distribution systems adds complexity to the calculation of the power flows and hence has a direct impact on the short circuit calculations, protection and control. The presence of unbalance in distribution systems worsens the situation since the three phase voltages and currents are no longer equal in magnitude and 120 degrees phase shifted.
This thesis involves a fault study in a 14-bus distribution system with integrated wind and solar power generation and shows the impact of unbalance in the system on short circuit calculations. The effect of unbalance on the behavior of traditional synchronous sources is already known and has been shown to cause errors in fault current magnitudes in the system. This thesis aims at observing and comparing the behavior of distributed generators in a balanced and an unbalanced distribution system. Detailed modeling of the DFIG and a grid connected PV array has been carried out in PSCAD. A 14 bus distribution system has been built and the distributed sources have been integrated into it. Unbalance has been introduced into an originally built balanced system by applying unbalanced loads at the buses and using untransposed feeders. Therefore, two systems, balanced and unbalanced, have been simulated and the behavior of the integrated distributed sources during faults has been compared for both the cases.

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